Grondmonsternemer

ABSTRACT

Soil sampler comprising a sampling tube having a receiving space for receiving the soil sample to be taken, the receiving space being limited in radial direction by a wall, being open in distal direction for permitting soil to enter in it and in proximal direction being limited by a transverse wall, having line means for supplying and discharging fluid to the receiving space and with means for closing off the line means, a free plug or piston being placed in the receiving space closely fitting in there and moveable between the transverse wall and the distal area of the sampling tube and the transverse wall and the stopper or piston defining a sealed chamber for fluid when the stopper or piston is situated at a distance from the transverse wall.

[0001] The invention relates to a soil sampler, as well as to a method for taking soil samples.

[0002] Soil samples are taken out at the desired depth by means of sampling tube, which is vibrated, screwed, driven etc, into the ground by means of a drill string attached to the upper end thereof, until the wanted depth is reached. At the distal end (the lower end) the sampling tube is provided with a valve, such as a cone, that is coupled to the sampling tube and closes off a receiving space for the soil. In order to receive the soil sample, an aid, such as a gripper, is lowered from above through the (hollow) drill string, with which the coupling between valve and sampling tube is disconnected. Subsequently the drill string including sampling tube is pressed deeper into the ground, room being made for the soil in the receiving space because the soil stops the valve with respect to the sampling tube.

[0003] Mechanic means such as balls, springs and pawls are used for the coupling/uncoupling of the valve to/from the sampling tube. Actual practice however shows that their action may quickly be impeded by soil particles.

[0004] An object of the invention is to improve on this.

[0005] A further object of the invention is to provide a soil sampler that is simple in build-up and is capable of working reliably also in the long term.

[0006] Another further object of the invention is to provide a soil sampler that is well-suited for taking soil samples in a layer below a layer of granular material.

[0007] To that end the invention provides, from one aspect, a soil sampler comprising a sampling tube having a receiving space for receiving the soil sample to be taken, the receiving space being limited in radial direction by a wall, being open in distal direction for permitting soil to enter in it and in proximal direction being limited by a transverse wall, having line means for supplying and discharging fluid to the receiving space and with means for closing off the line means, a free plug or piston being placed in the receiving space closely fitting in there and moveable between the transverse wall and the distal area of the sampling tube and the transverse wall and the stopper or piston defining a sealed chamber for fluid when the stopper or piston is situated at a distance from the transverse wall.

[0008] Thus use is made of a fluid body—that cannot be compressed—for stopping the soil during bringing the end of the sampling tube to the wanted starting level. When the soil has to be let in the fluid can simply be let to escape via the line means. Mechanic provisions at the distal end of the sampling tube are no longer necessary then. Long-term reliable action is guaranteed. The stopper or plug or piston has the same function as the cone already known, but in itself is freely slidable within the receiving space, without connection means to the sampling tube. When sampling has to take place through one or several layers of material, particularly granular material, the receiving space can remain closed off until the starting level for taking the soil sample has been reached.

[0009] Preferably the stopper or piston has a distal surface that is a part of the front surface of the soil sampler, and it preferably has a conical distal surface, when the consistency of one or more of the soil layers necessitate a pointed-shaped end for penetration therein.

[0010] Preferably the stopper or piston is provided with a cavity in at least one of its axially oriented surfaces. As a result the press force against the radial boundary of the receiving space and thus the sealing against fluid is improved and/or against passage of soil material past the stopper or piston.

[0011] Optimisation of the sealing against fluid leakage is obtained when the stopper or piston at the proximal side is in liquid-sealing engagement with the wall surface of the receiving space according to a line shaped contact.

[0012] A comparable measure can be taken at the distal side of the stopper or piston for counteracting soil leakage.

[0013] In that connection it is preferred that the stopper or piston has a diabolo-like or hourglass shape.

[0014] Preferably the line means comprise a fluid duct extending through the transverse wall, a valve that can be remote controlled being present for selectively opening the fluid duct. Preferably the valve is a one-way valve that is biassed against the distal end of the fluid duct. It is furthermore preferred that the valve comprises a valve disc and a valve rod connected thereto, the valve rod extending through the fluid duct to the proximal side of the transverse wall and being biassed at that location by means of a compression spring. Preferably the fluid duct is adapted here for selective discharge of fluid from the receiving space. When the receiving space is filled with fluid the valve will prevent its escape. When it is desirable—at depth—to let the fluid escape, the valve is operated, for instance by pressing in the valve rod by means of a lowered weight, so that the fluid can flow out of the receiving space, corresponding to the volume of the soil taken in.

[0015] Discharge and discharge of the fluid can take place via the same duct. It is preferred however that the line means comprise a separate and closable supply duct for fluid.

[0016] The supply duct also renders it possible to supply fluid to the receiving space after raising the soil sampler in order to press out the soil sample situated in there.

[0017] Preferably the sampling tube is provided with a core catcher at the distal end in order to prevent that material of a soil sample of non-cohesive material spills out after the soil sample has been taken.

[0018] It may be desirable to pack the soil sample. To that end, according to the invention, means are provided for at least radially enveloping the soil sample to be received in the receiving space.

[0019] In an embodiment the enveloping means comprise a sleeve arranged at the distal end of the sampling tube such that it can be unwound and extending with a closed end over the open distal end of the receiving space. The sleeve can then be pulled along and unwound by the entering soil.

[0020] In case there is a stopper or piston it may be advantageous in the preparation of the soil sampler that the stopper or piston is connected to the sleeve.

[0021] In an alternative embodiment a liner is placed in the sampling tube, which liner covers the inner surface of the sampling tube at the location of the receiving space. Said liner is already at the wanted place prior to the soil sample being taken. It is preferred here that a fluid seal is placed between the liner and the sampling tube in order to close off a possible leakage path for the fluid in the receiving space.

[0022] Preferably the stopper or piston is in engagement with the inner surface of the liner.

[0023] From another aspect the invention provides a method for taking soil samples, wherein a sampling tube having an open end giving access to a receiving space for the soil sample is being filled with fluid, is forced into the ground in that state until the location is reached from where the soil sample has to be taken, the fluid is given the opportunity to escape while pushing the sampling tube deeper into the ground so that the wanted soil enters the receiving space.

[0024] From a further aspect the invention thus provides a method of the kind just described wherein the fluid filled receiving space is sealed to the outside with a fluid sealing free piston, wherein the soil moves the piston to the inside while urging the fluid out when the soil enters.

[0025] In the known soil samplers after disconnecting the cone, soil samples can only be taken from the location where that has taken place. One or several of the preferred constructions according to the invention discussed above, however, render it possible to close off the receiving space again at any wanted moment, so that fluid remains in it and the soil already taken in as it were forms a sealing at the distal end of the sampling tube.

[0026] From a further aspect the invention to that end provides that the receiving space is only partially filled with soil, the fluid is stopped again from escaping, the sampling tube is urged further into the ground down to a lower spaced apart location is reached where soil is present of which a sample has to be taken as well, the fluid is given the opportunity again to escape while pushing the sampling tube deeper into the ground so that there as well the wanted soil enters the receiving space.

[0027] After the soil sampler has been raised the receiving space preferably is filled with a pressurised fluid to urge the soil sample taken, out of the sampling tube.

[0028] The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings, in which:

[0029]FIG. 1 is a longitudinal section of the lower end of a first embodiment of a sampler according to the invention;

[0030]FIG. 1A is a cross-section of a free piston as used in the embodiment of the sampler according to FIG. 1;

[0031]FIG. 2 is a longitudinal section of the lower end of a second embodiment of the sampler according to the invention;

[0032]FIG. 3 is a longitudinal section of a portion of a third embodiment of the sampler according to the invention; and

[0033]FIG. 4 is a longitudinal section of a portion of a fourth embodiment of the sampler according to the invention.

[0034] In FIG. 1 a sampler 1 is shown having a stainless steel sampling tube 2 having a length of for instance 1.5 metres and a cutting shoe 3 made of hardened metal with a sharp cutting angle, which shoe is screwed to the lower end of the sampling tube via threaded connection 23. The cutting shoe 3 defines a passage 4 to the inside of the sampling tube 2.

[0035] In a manner not shown here, a core catcher 5 is attached to the inner surface of cutting shoe 3, that is provided with lips 6, that can be bent away radially to the outside to allow soil to pass in upward direction but prevent movement of said soil in downward direction. Said core catchers are generally known and are specifically used when a sand sample has to be taken.

[0036] The sampling tube 2 forms a chamber 7 that is bounded at the upper end by a wall 9. In the wall 9 a valve 10 is present that abuts the seat 12 for sealing and is provided with a valve rod 11 that is biassed in upward direction by means of spring 13, so that the valve 10 seals off the passage 28 around the valve rod 11. The wall 9 is furthermore provided with a duct 14 extending from the chamber 7 to the outside and is closed off here by means of removable plug 15.

[0037] Above the wall 9 the sampling tube 2 is provided with a screw thread 26 for connection to a drill string that is not further shown.

[0038] The chamber 7 further offers room to a free piston, which for instance is made of hard rubber, and is further shown in FIG. 1A. It can be seen that the piston 8 has a more or less diabolo-like or hourglass shape having an uppermost circumferential edge 16 and a lowermost circumferential edge 17, and moreover at the top side and the bottom side is provided with cavities 18 and 19.

[0039] The use of the sampler 1 with sampling tube 2 of FIG. 1 can take place as follows. Above ground level the plug 15 is removed and a source for—incompressible—fluid such as water, is connected to duct 14. Said fluid flows into the chamber 7 under pressure, and will move the piston 8 to the distal end portion of the sampling tube 2. When it is established that the piston 8 has been moved far enough towards the distal end the duct 14 is closed off by plug 15. In that situation the chamber 7 is upwardly closed off by the valve 10 and downwardly closed by the piston 8. The shape of the piston 8, because of the cavity 18 and because of the line-shaped contact 16, prevents downward leakage of the fluid past the circumference of the piston 8. The piston is kept in its place by friction with the sampling tube wall and by the influence of the closed-off, water-filled chamber 7.

[0040] Subsequently the soil sampler 1 including sampling tube 2 and cutting shoe 3 are inserted into the ground and it is pushed by means of the drill string to almost above the layer of which the soil sample has to be taken. Arrived there, a weight or another operating means (such as a rod) is lowered through the (hollow) drill string in order to press the end of the valve rod 13 downwards. For instance a stone having a weight of 1 kg on a wire, when the soil sampler is screwed into the ground and the spring pressure of the valve need not be high. When vibrating takes place, the spring pressure could for instance be 10 kg and a rod is recommendable. As a result of the downward movement of the valve rod 13 the valve 10 opens in the direction A and in case of further downward movement of the sampler 1 the piston 8 will be able to move upward in the direction B because the fluid is able to flow out of the chamber 7, through the wide passage 28 for the valve rod 13, to the hollow space above the wall 9. Thus room is made within the sampler 1 for soil entering via the passage 4.

[0041] When urging the piston 8 upward under the influence of the soil pressure, the circumferential edge 17 together with a line-shaped contact and the cavity 19 ensures that no soil material can move upwards past the piston 8.

[0042] When the piston 8 is moved upwards to the inside of the sampling tube 2 to a desirable degree, the valve rod 13 is unloaded again, and the chamber 7 is closed again. The sampler can be raised again then, the piston and the column of soil hanging under it being secured against sagging out. In the chamber 7 a vacuum may arise which offers an upward force against the soil sample sagging.

[0043] In case of non-cohesive material such as coarse sand, further securing is provided by the core catcher 5.

[0044] After the soil sampler 1 has been brought above ground level the plug 15 can be removed and water be pressed in through it again in order to urge the piston 8 and thus the soil sample in the chamber 7 to the distal end and (but not the piston) out of it.

[0045] Consecutive samples can be taken from soil layers that are situated at different depths as well. In that case, for instance when the piston has come halfway of the original chamber 7, weight will be removed earlier from the valve rod 13 and then the sampler 1 is pressed further downward into the ground, the lower end of the soil sample taken then forming the end plane of the sampler 1. Possibly the soil will be compressed here a to some extent, though this can be taken into account in the analysis of the soil sample.

[0046] When, for instance after having penetrated into the soil two metres further down, the top of the next layer to be sampled has been arrived at, weight can be brought onto the valve rod 13 again to open the valve 10 and subsequently by pressing in the sampler 1 further in the soil, taking the next (partial) sample. The same method is used then. Finally, in the manner discussed above, the sampler 1 can be raised again after taking all the wanted soil samples.

[0047] In FIG. 2 it is shown in which way the sampler 1 can also be given a pointed shape, when such is necessary for the penetration in the soil in question. At the lower surface of the piston 8 a hard rubber cone 10 with tip 21 is placed to that end. Said cone can form a separate part (possibly glued to it) with respect to the piston 8, only to be deployed when the soil in question necessitates such. Further the operation of this embodiment is the same as the one of FIG. 1, it being noted that when taking the samples the volume of the cone 20 should of course be taken into account.

[0048] In FIG. 3 a sampler according to the invention is shown, the soil sample being packed immediately in a so-called sleeve. To that end the shoe 3 is extended in proximal direction and it forms an annular chamber 27 with the extended sampling tube 2. An end of a permeable nylon sleeve 21 that is rolled up there is attached in that chamber, the annular chamber 27 thus offering room to a stock 21a of the sleeve 21. The sleeve 21 extends downwards and extends about the lower end of the sampling tube 2 to the inside and upwards, in order to be closed with the other end. Possibly said end of the sleeve can be attached to the piston 8 at the location of 22.

[0049] When the valve 10 is opened and the sampler 1 is urged downwards into the ground, the soil entering the space below the piston 8 will move the piston 8 upwards and also move along the end of the sleeve 21 upwards, the sleeve being able to unwind from the stock 21 a accommodated in the annular chamber 27, until the wanted sample length is achieved. After raising the sampler and after screwing the cutting shoe 3 off, the portion of the sleeve that is situated at the outside of the sampling tube 2 can be engaged to make a sleeve sealing there.

[0050] In FIG. 4 the arrangement is shown in which use is made of a so-called rigid liner or tubing 24, which liner is also used for the packing of a soil sample. The—possibly transparent—liner 24 is accommodated in the sampling tube 2 and forms a radial boundary of the chamber 7. The piston 8 here moves within the liner, in the same manner as is the case in the embodiment of FIG. 1. Between the cutting shoe 3 and the liner 24, the core catcher 5 is fixed with a flange 26. In order to prevent downward escape of fluid 7 via the upper edge of the liner 24 and past the outer surface of the liner 24 and the inner surface of the sampling tube 2, a sealing or O-ring 25 is placed at the bottom between the outer surface of the liner 24 and either the sampling tube 2 or cutting shoe 3. As a result the liners can be thin-walled and have a continuous profiling without treatments.

[0051] In the above preferred embodiments of the invention have been described. It is to be understood that the invention is not limited to them and that modifications and changes can be made without going beyond the spirit and scope of the following claims. 

1. Soil sampler comprising a sampling tube having a receiving space for receiving the soil sample to be taken, the receiving space being limited in radial direction by a wall, being open in distal direction for permitting soil to enter in it and in proximal direction being limited by a transverse wall, having line means for supplying and discharging fluid to the receiving space and with means for closing off the line means, a free plug or piston being placed in the receiving space closely fitting in there and moveable between the transverse wall and the distal area of the sampling tube and the transverse wall and the stopper or piston defining a sealed chamber for fluid when the stopper or piston is situated at a distance from the transverse wall.
 2. Soil sampler according to claim 1, the stopper or piston having a distal surface that is a part of the target surface of the soil sampler.
 3. Soil sampler according to claim 2, the stopper or piston having a conical distal surface.
 4. Soil sampler according to claim 1, the stopper or piston being provided with a cavity in at least one of its axially oriented surfaces.
 5. Soil sampler according to claim 4, the proximal surface of the stopper or piston being provided with a cavity.
 6. Soil sampler according to claim 1, the stopper or piston at the proximal side being in liquid-sealing engagement with the wall surface of the receiving space according to a line shaped contact.
 7. Soil sampler according to claim 6, the stopper or piston having a diabolo-like or hourglass shape.
 8. Soil sampler according to claim 1, the line means comprising a fluid duct extending through the transverse wall, a valve that can be remote controlled being present for selectively opening the fluid duct.
 9. Soil sampler according to claim 8, the valve being a one-way valve that is biassed against the distal end of the fluid duct.
 10. Soil sampler according to claim 9, the valve comprising a valve disc and a valve rod connected thereto, the valve rod extending through the fluid duct to the proximal side of the transverse wall and being biassed at that location by means of a compression spring.
 11. Soil sampler according to claim 10, the fluid duct being adapted for selective discharge of fluid from the receiving space.
 12. Soil sampler according to claim 11, the line means comprising a separate and closable supply duct for fluid.
 13. Soil sampler according to claim 1, the sampling tube at the distal end being provided with a core catcher.
 14. Soil sampler according to claim 1, furthermore provided with means for at least radially enveloping the soil sample to be received in the receiving space.
 15. Soil sampler according to claim 14, the enveloping means comprising a sleeve arranged at the distal end of the sampling tube such that it can be unwound and extending with a closed end over the open distal end of the receiving space.
 16. Soil sampler according to 15, the stopper or piston being connected to the sleeve.
 17. Soil sampler according to claim 14, a liner being placed in the sampling tube, which liner covers the inner surface of the sampling tube at the location of the receiving space.
 18. Soil sampler according to claim 17, a fluid seal being placed between the liner and the sampling tube.
 19. Soil sampler according to claim 17, the stopper or piston being in engagement with the inner surface of the liner.
 20. Method for taking soil samples, wherein a sampling tube having an open end giving access to a receiving space for the soil sample is being filled with fluid, is forced into the ground in that state until the location is reached from where the soil sample has to be taken, the fluid is given the opportunity to escape while pushing the sampling tube deeper into the ground so that the wanted soil enters the receiving space.
 21. Method according to claim 20, wherein the fluid filled receiving space is sealed to the outside with a fluid sealing free piston, wherein the soil moves the piston to the inside while urging the fluid out when the soil enters.
 22. Method according to claim 20, wherein the receiving space is only partially filled with soil, the fluid is stopped from escaping, the sampling tube is urged further into the ground down to a lower spaced apart location is reached where soil is present of which a sample has to be taken as well, the fluid is given the opportunity again to escape while pushing the sampling tube deeper into the ground so that there as well the wanted soil enters the receiving space.
 23. Method according to claim 20 wherein after the soil sampler has been raised the receiving space is filled with a pressurised fluid to urge the soil sample taken, out of the sampling tube. 